1. Field of the Invention
This application relates broadly to liquid purification systems and methods, such as treating water to clarify it for potable or industrial use. More particularly, it concerns flocculator/clarifier systems and methods for treating water and other liquids contaminated with suspended solids and/or dissolved solid materials.
2. Description of the Prior Art
Huge volumes of liquids must be treated daily to remove suspended solids and/or dissolved solid materials so that they will be rendered acceptable for potable or industrial use. A prime example is the daily treatment by municipalities of vast quantities of water from a variety of sources containing suspended solids which must be removed before the water can delivered to their customers. However, there are many other types of liquids handled in large quantities that must be treated to remove suspended or dissolved solids.
Numerous different types of equipment have been developed for treating large volumes of liquids for solids removal in an efficient and economical manner. One leading industrial type is marketed by Infilco Degremont Inc., the assignee of the present invention, under the trademark DensaDeg.RTM. Clarifier which is described in an IDI brochure No. DB-555, dated March 1990, the contents of which are incorporated herein by reference. This equipment combines mixing, internal and external solids recirculation, sludge thickening and lamellar clarification, in two conjoined vessels. The design of the treatment vessels is such that each compliments the performance of the other to the point that either vessel requires the other in order to optimize unit operation and treatment results. One of the conjoined vessels is a so-called reactor into which influent is charged and acted upon by a motor driven turbine running within a draft tube.
The present invention provides improvements to the DensaDeg.RTM. Clarifier by the elimination of the motor driven turbine with attendant savings in maintenance of the turbine and related elements operating submerged in an adverse environment. Thus, a great concern with any clarifier type equipment is the formation of scale in lime addition applications. With mechanical units, which employ turbine blades, shafts, etc., which expose a lime slurry (in turbulence) to air, there is a greater tendency to form scale than where the slurry is hydraulically driven without exposure to air.
Liquid treatment systems for suspended solids removal that are hydraulically driven for admixture of flocculants and other treating chemicals with the influent are known, e.g., see U.S. Pat. Nos. 4,146,471; 4,765,891 and a brochure of the Walker Process Corporation of Aurora, Ill. entitled ClariCone.TM. (Bulletin 5W85). The present invention provides an improved form of hydraulically driven liquid treatment apparatus.